This invention relates to an improved retorting process for the production of oil from oil shale and like materials.
It has been known for many years that a refinable hydrocarbonaceous oil can be produced by retorting oil shale and other solid hydrocarbonaceous and lignocellulosic materials. The commercialization of such processes is intimately dependent upon the yield of oil obtained per ton of starting material, the cost of the capital equipment required to conduct the process and, to a lesser extent, upon the ecological impact of the process upon the surrounding environment. I have now found that an improved yield of oil of higher quality is achieved with lower energy consumption by conducting the retorting process in the presence of steam and acetic acid.
U.S. Pat. No. 2,966,450 (Kimberlin et al.) mentions the use of acetic acid in conjunction with solvents for extracting oil from shale, but states it is unsuitable for this purpose. U.S. Pat. No. 2,560,767 (Huff), U.S. Pat. No. 2,710,828 (Scott), U.S. Pat. No. 2,832,725 (Scott) and U.S. Pat. No. 4,075,083 (Putman) all disclose methods for retorting oil shale where the particulate solids are passed down through a treating vessel, through a preheating zone, and through zones of progressively higher temperatures. Huff discloses a means whereby hot air from the end of the process is recycled to the preheat zone.